One-dimensional carbon nanotube (CNT) exhibits excellent mechanical properties and is considered to be an ideal candidate material for the space elevator. However, subtle changes in its chirality strongly affect its physical and chemical properties, including mechanical properties (such as Young's modulus. For short YM). Theoretical studies reveal that the YMs of perfect single-walled carbon nanotubes (SWCNTs) are in the order of TPa and related to their structures. Nevertheless, due to the lack of SWCNTs samples with well-defined structures and the difficulties in mechanical tests on individual SWCNTs, the theoretical correlations between YM and structure of SWCNTs have not been verified and are still in debate, which directly influences the practical utilization of the excellent mechanical properties of SWCNTs. In this work, we have developed an experimental method to measure the YM of an individual micrometer-scale suspended CNT by atomic force microscopy. A distinct regularity is found between the YM and chirality (i.e., chiral angle and diameter) of SWCNT in the experiment for the first time. By comparing the YMs of SWCNTs with similar diameters and different chiral angles, it manifests that the SWCNT with a near zigzag configuration has a larger YM. This finding suggests that the effect of SWCNT’s structures on the YMs cannot be ignored. The developed method of measuring YMs of SWCNTs will be valuable for further experimental research on the inherent physical and chemical properties of SWCNTs.

Transparent photovoltaic devices (TPVDs) have attracted increasing attention in emerging electronic devices. As the application scenarios extend, there raises higher requirements regarding the stability and operating temperature range of TPVDs. In this work, a unique preparation strategy is proposed for air stable TPVD with a wide operating temperature range, i.e. a nanoscale architecture termed as H-TPVD is constructed that integrates a free-standing and highly transparent conductive hybrid film of graphene and single-walled carbon nanotubes (G-SWNT TCF for short) with a metal oxide NiO/TiO₂ heterojunction. The preparation approach is suitable for scaling up. Thanks to the excellent transparent conductivity of the freestanding G-SWNT hybrid film and the ultrathin NiO/TiO₂ heterojunction (100 nm), H-TPVD selectively absorbs the UV band of sunlight and has a transparency of up to 71% in the visible light. The integrated nanoscale architecture manifests the significant hole-collecting capability of the G-SWNT hybrid film and the efficient carrier generation and separation within the ultrathin NiO/TiO₂ heterojunction, resulting in excellent performance of the H-TPVD with a specific detectivity of 2.7 × 10¹⁰ Jones. Especially, the freestanding G-SWNT TCF is a super stable and non-porous two-dimensional film that can insulate gas molecules, thereby protecting the surface properties of NiO/TiO₂ heterojunctions and enhancing the stability of H-TPVD. Having subjected to 20,000 cycles and storage in air for three months, the performance parameters such as photo-response signal, output power, and specific detectivity show no noticeable degradation. In particular, the as-fabricated self-powered H-TPVD can operate over a wide temperature range from -180°C to 300°C, and can carry out solar-blind UV optical communication in this range. In addition, the 4×4 array H-TPVD demonstrates clear optical imaging. These results make it possible for H-TPVD to expand its potential application scenarios.

Despite the ever-increasing demand of nanofillers for thermal enhancement of polymer composites with higher thermal conductivity and irregular geometry, nanomaterials like carbon nanotubes (CNTs) have been constrained by the nonuniform dispersion and difficulty in constructing effective three-dimensional (3D) conduction network with low loading and desired isotropic or anisotropic (specific preferred heat conduction) performances. Herein, we illustrated the in-situ construction of CNT based 3D heat conduction networks with different directional performances. First, to in-situ construct an isotropic percolated conduction network, with spherical cores as support materials, we developed a confined-growth technique for CNT-core sea urchin (CNTSU) materials. With 21.0 wt.% CNTSU loading, the thermal conductivity of composites reached 1.43 ± 0.13 W/(m·K). Secondly, with aligned hexagonal boron nitride (hBN) as an anisotropic support, we constructed CNT-hBN aligned networks by in-situ CNT growth, which improved the utilization efficiency of high density hBN and reduced the thermal interface resistance between matrix and fillers. With ~ 8.5 wt.% loading, the composites possess thermal conductivity up to 0.86 ± 0.14 W/(m·K), 374% of that for neat matrix. Due to the uniformity of CNTs in hBN network, the synergistic thermal enhancement from one-dimensional (1D) + two-dimensional (2D) hybrid materials becomes more distinct. Based on the detailed experimental evidence, the importance of purposeful production of a uniformly interconnected heat conduction 3D network with desired directional performance can be observed, particularly compared with the traditional direct-mixing method. This study opens new possibilities for the preparation of high-power-density electronics packaging and interfacial materials when both directional thermal performance and complex composite geometry are simultaneously required.

Compared with piezoresistive sensors, pressure sensors based on the contact resistance effect are proven to have higher sensitivity and the ability to detect ultra-low pressure, thus attracting extensive research interest in wearable devices and artificial intelligence systems. However, most studies focus on static or low-frequency pressure detection, and there are few reports on high-frequency dynamic pressure detection. Limited by the viscoelasticity of polymers (necessary materials for traditional vibration sensors), the development of vibration sensors with high frequency response remains a great challenge. Here, we report a graphene aerogel-based vibration sensor with higher sensitivity and wider frequency response range (2 Hz–10 kHz) than both conventional piezoresistive and similar sensors. By modulating the microscopic morphology and mechanical properties, the super-elastic graphene aerogels suitable for vibration sensing have been prepared successfully. Meanwhile, the mechanism of the effect of density on the vibration sensor’s sensitivity is studied in detail. On this basis, the sensitivity, signal fidelity and signal-to-noise ratio of the sensor are further improved by optimizing the structure configuration. The developed sensor exhibits remarkable repeatability, excellent stability, high resolution (0.0039 g) and good linearity (non-linearity error < 0.8%) without hysteresis. As demos, the sensor can not only monitor low-frequency physiological signals and motion of the human body, but also respond to the high-frequency vibrations of rotating machines. In addition, the sensor can also detect static pressure. We expect the vibration sensor to meet a wider range of functional needs in wearable devices, smart robots, and industrial equipment.

In order to develop an excellent pseudocapacitor with both high specific capacitance and outstanding stretchability to match with other devices applicable in future wearable and bio-implantable systems, we focus our studies on three vital aspects: Stretchability of hybrid film electrodes, the interface between different components, and the integrated performance in stretchability and electrochemistry of supercapacitors based on single-walled carbon nanotube/polyaniline (SWCNT/PANI) composite films on pre-elongated elastomers. Owing to the moderate porosity, the buckled hybrid film avoids the cracking which occurs in conventional stretchable hybrid electrodes, and both a high specific capacitance of 435 F·g^-1 and a high strain tolerance of 140% have been achieved. The good SWCNT/PANI interfacial coupling and the reinforced solid electrolyte penetration structure enable the integrated pseudocapacitors to have stretch-resistant interfaces between different units and maintain a high performance under a stretching of 120% elongation, even after 1, 000 cyclic elongations.